The present invention relates to a portable label printer having two printing mechanisms for printing on two different rolls of paper or label stock, and relates particularly to a portable label printer having two printing mechanisms in which each printing mechanism is located in a module detachable from the printer. The printer is suitable for printing on two different types of paper in a single miniature integrated unit. The printer operates interactively with a host computer or a terminal. One type of portable terminal is attachable to the printer of the present invention and can operate as an optical scanner or a communication device.
Conventionally, portable miniature label printers have a single print head, such as a thermal printhead, for enabling printing on a single roll of paper or label stock. Examples of portable single printhead printers are described in U.S. Pat. Nos. 5,267,800, 5,806,993, and 5,594,838. One drawback of such printers is that they are limited to printing on only one type of paper at a time from the roll in the printer. Thus, a user of the printer must switch between rolls of different types of paper, which requires time and dexterity to open and reload the paper in the printer. Further, the printer may need to be reprogrammed to provide printing on different types of labels. To avoid switching between rolls, multiple label printers can alternatively be carried by a user. However, this is expensive as it requires purchasing multiple portable printers capable of printing on different rolls. Thus, it would be desirable to provide a label printer having two printheads which are capable of printing on two different types of paper from two different rolls.
Two printheads have been used in Point of Sale (POS) stations in the retail industry, such as described for example in U.S. Pat. No. 5,782,567. These POS stations often have printing devices limited to enabling printing of customer receipts from a roll of paper, and a record of each sale on another roll of paper which is stored on a take-up reel in the printer. Similarly, U.S. Pat. No. 4,747,707 describes a label printer having a first printing device for printing a label, and a second printing device for printing on record paper stored on a take-up shaft in the printer. The second printing device in each of these patents is limited to recording the same information as the first printing device, and thus is not operated independently from the first printing device.
Furthermore, as only one of the printing devices can actually print a label for a user, this printer has the same drawback as the single printhead label printer.
Further, the printhead in a portable label printer is fixably mounted and thus cannot be easily changed or replaced by the typical user if either the printhead is damaged or a different width printhead is needed. Accordingly, it is further desirable to provide a portable printer in which the entire printing mechanism, including the printhead, is in a module which can easily be replaced with another a module having another printing mechanism.
Accordingly, it is a principal object of the present invention to provide an improved portable printer capable of printing from two different rolls of paper or label stock contained in the printer.
It is another object of the present invention an improved portable printer which is miniature.
A further feature of the present invention is to provide a portable printer having a printing mechanism enclosed in a module which can be easily replaced with another module having another printing mechanism.
Briefly described, a portable printer embodying the present invention includes a housing having a central control section with printer control circuitry, and first and second printing sections coupled to the central section. Each of the first and second printing sections has a printing mechanism with a thermal printhead and a driving motor, and a compartment for receiving a roll of paper. The compartment of each of the first and second printing sections has a hinged cover enabling loading of the roll of paper when the cover in an open position. A platen roller is rotatably mounted in the cover, such that when the cover is in a closed position, the surface of the platen roller faces the printhead and the platen roller is rotationally coupled with the driving motor to drive the paper from the roll across the printhead. The printer control circuitry of the central control system independently controls the printing of the printing mechanism, including actuation of the driving motor, of each of the first and second printing sections interactive with signals from a host computer or terminal. Each of the first and second printing sections represents a module detachable from the central control section which can be replaced with a module providing another printing section. Different modules may be capable of accommodating printing on the same or different types of paper, and may have a different width printhead and roll receiving compartment to print on paper having different widths.
A portable terminal may be attached to the central control section of the printer to communicate with the printer control circuitry. The terminal may have circuitry for enabling RF, LAN, voice over Internet, or cell-phone communication, or for enabling optical scanning through a window of the terminal. The terminal may be detached from the housing to facilitate its use as a communication device or optical scanner. The printer may operate in accordance with commands and data received from the portable terminal, or other terminal or host computer, to send signals to each of the printing mechanisms to print data.
In an another embodiment of the printing sections, each of the first and second printing sections has a printing mechanism with a driving motor, a compartment for receiving a roll of paper, and a hinged cover having a thermal printhead. A platen roller is rotatably mounted in the printing mechanism and rotationally coupled with the driving motor. The cover in an open position enables loading of the roll of paper, and in a closed position, the printhead of the cover faces the surface of the platen roller such that the platen roller can drive the paper from the roll across the printhead. Each of the first and second printing sections can accommodate different width paper by an automatic centering mechanism having two edge guides which retain the roll about its core and are coupled to each other to automatically center the roll with respect to the printhead.
The portable printer of the present invention, in contrast with prior portable label printers, is capable of independently printing on different information on two different rolls. Thus, the printer of the present invention is more flexible than prior art portable printers.